The present invention relates to a new and improved construction of centrifugal casting arrangement for a centrifugal casting machine, especially for dental applications, as well as to an improved construction of housing structure for use in such centrifugal casting machine.
Centrifugal casting machines of the aforementioned general type are well known in the art. For instance, centrifugal casting machines suitable for use in dentistry have been disclosed, for instance, in German Patent Publication No. 2,020,910, published Nov. 18, 1971, German Patent Publication No. 2,932,543, published Feb. 14, 1980, and the published brochure of the well known German company Degussa Corporation, entitled "Tiegelschleuder Ts 3". Such type of centrifugal casting machines are typically used in dental laboratories for fabricating artificial dentures or parts thereof, such as prosthesis and cast parts formed of noble metals or replacement materials. Seated upon a centrifuge or centrifugal arm of such centrifugal casting machine is a muffle or retort holder which can be elevationally adjusted and serving for supporting casting muffles or retorts of different sizes. Also seated upon such centrifuge arm is a compensation or balancing mass which can be locked at appropriate positions upon the centrifuge arm in accordance with the momentarily employed muffle mass. Additionally, such type of centrifugal casting equipment uses a melting crucible or a melting trough. Both the muffle holder and the compensation mass or weight, depending upon the size of the muffle or retort, must be placed in a correct position, in order to eliminate as far as possible any imbalance during the centrifugal casting operation.
With such state-of-the-art equipment the centrifuge or centrifugal arm is secured in horizontal position upon a vertical shaft or axle of a drive element, for instance a spiral spring or a drive motor and optionally accommodated within a housing. Such known constructions of centrifugal casting machine no longer fulfil the present day requirements as concerns protection against accidents and ease in operation. The tightening of the drive spring of the centrifuge arm, the manipulations carried out at such centrifuge arm when the spring is tensioned as well as the operation of the centrifugal casting machine, is dangerous. Additionally, particularly in the case of motor-driven centrifugal casting machines, the compensation or balancing mass is not adjusted by the operating personnel to the size of the momentarily employed muffle or retort. Hence, due to the high circumferential velocity of the centrifuge arm the entire centrifugal casting machine is markedly mechanically loaded because of the prevailing imbalance, and hence must be mounted in an extremely solid or sturdy fashion in order to avoid the production of faulty castings due to the vibrations which arise.